This invention pertains to methods and apparatus for model testing in wind tunnels and, more particularly, to method and apparatus for use in wind tunnel testing of models which utilize reaction control systems.
Reaction control systems are used to orient vehicles in flight under conditions in which aerodynamic control devices are ineffective. Such conditions particularly occur during the flight of manned and unmanned vehicles in the upper regions of the atmosphere or in space. Reaction control jets are generally placed on both the right and left sides and in the nose and aft sections of the vehicle to provide pitch, yaw, and roll control.
The design of space vehicles requires extensive testing to ascertain the flight characteristics and response of each particular vehicle design. An arrangement of reaction control jet thrusters is first defined and the response of the model to that particular configuration is experimentally determined. A variety of such configurations are designed and tested whereby the optimum performance characteristics relative to the model response to the reaction control system can be ascertained.
It has been conventional to fabricate a series of individual reaction control system model nozzle blocks each containing a particular jet nozzle thruster arrangement for each test. A large plenum was provided for each jet thruster arrangement to ensure proper flow of the thrusting medium to the nozzles. The large plenum necessitated individual nozzle blocks since individual jets could not then be controlled and, further, the size of the nozzle block would become enlarged if alternate jets were incorporated. The thrust characteristics of each test configuration had to be calibrated and the individual thrusters on each nozzle block adjusted to provide predetermined thrust characteristics.
Separate reaction control system nozzle blocks were, therefore, fabricated for each thruster configuration under consideration. Such individual fabrication and adjustment, as hereinabove discussed, is costly since the manufacture and calibration of the reaction control model test blocks requires a high degree of precision. Further, extensive model testing down-time is required to install and align each new model test nozzle block on the model.
These disadvantages of the prior art are overcome by the present invention, and an improved method and apparatus are provided for reaction control system testing of space vehicles during simulated performance testing in wind tunnels.